A medical institution is equipped with a radiation tomography apparatus for picking up tomographic images of a subject with radiation. Examples of such a radiation tomography apparatus include a PET (Positron Emission Tomography) apparatus configured to image radiopharmaceutical distribution within a subject. See, for example, Japanese Patent Publication (Translation of PCT Application) No. 2009-528139A.
Data obtained with the PET apparatus is three-dimensional data representing distribution intensity of radiopharmaceutical three-dimensionally. MIP imaging is one method of representing the three-dimensional data simply and conveniently as a two-dimensional image.
Description will be given of generating an MIP image. Three-dimensional data obtained with the PET apparatus contains a stereoscopic image of a subject. Here, a plane F relative to the stereoscopic image is to be considered. Next, a line N is to be considered. The line N passes through the plane F vertically and passes through the stereoscopic image V. See FIG. 10. The plane F is drawn as a line in FIG. 10 since the plane F is orthogonal to the plane of FIG. 10.
Here, considered is one of voxels of the stereoscopic image V on the line N. The voxel is a constitutional unit of three-dimensional data and corresponds to a pixel of a two-dimensional image. The voxel on the line N having the highest intensity corresponds to the maximum intensity of the line N.
The MIP image is obtained by placing the maximum intensity of the line N on an intersection Q of the line N and the plane F. That is, the maximum intensity of a plurality of lines parallel to the line N passing through the plane F is selected and placed successively, whereby an MIP image is generated. The MIP image generated in this way is an image with a remarkable configuration in the stereoscopic image V projected on the plane F.
Diagnosis with the MIP image allows rough determination of a portion of the subject where radiopharmaceutical concentrates. When the subject has inside thereof a concentrated portion of the radiopharmaceutical, it is determined that voxels with high intensity are collected in a portion of the three-dimensional data corresponding to the concentrated portion. The MIP image is generated while such the high intensity of the voxels is collected. Accordingly, diagnosis with the MIP image allows simple and convenient determination of a portion with high intensity in the three-dimensional data.